textproduct: Rapid City

KEY MESSAGES

-Winter storm to impact the region tonight through Friday

-Unsettled westerly flow will then persist through next week with fluctuating temperatures, mostly on the warm side of normal

DISCUSSION

(This Afternoon Through Wednesday) Issued at 1148 AM MDT Thu Apr 2 2026

Dominant northern stream flow expected through the period with embedded stronger upper troughs at times. Once such upper trough will advect into the region later today/tonight supporting increasing chances for rain/freezing rain/and snow. Pos theta-e adv ongoing ahead of this system with decently steep mid level lapse rates. Strong lift from the upper trough combined with a potent jet streak will support increasing chances for showers with isolated thunderstorms later this afternoon into the overnight, best chances across the western half. As the upper trough shifts east and organizes, FGEN bands will develop, one over the west SD Plains, and another across northeast WY into NW SD. CAA under the warm nose across western SD will support a window of freezing rain, with some icing possible later tonight, esp toward central SD over Haakon into scentral SD. Further west a smaller window of freezing rain will be possible with a light glaze of ice accums. As deeper CAA ensues Friday morning, precip will transition to all snow NW-SE with accums expected to start in the adv and warning areas. Highest snow amounts will be across NW SD where accums could total around 10 inches in Perkins County. There is a little uncertainly with respect to snow amounts along I90, where the NAM has shifted south with snow accums, esp around the Black Hills. Most guidance keeps snow amounts there under 3 inches on the Plains outside of the northern foothills. Another area of uncertainty is the northeast WY Plains, esp Campbell County. Some models suggest local amounts up to 8 inches will be possible there. But given snowfall rates are not expected to be on the extreme end of the scale with most of the snow falling during the day, snow will likely settle and melt some as it falls limiting amounts in these locations. Winds do not look to terrible with some gusts up to 35 mph for period Friday across far western SD and northeast WY. Hence, some blowing snow is possible. Have upgraded the winter storm watch to a warning and added winter weather adv's a few zones to the south. System will quickly lift out Friday night with snow ending. Temps warm back up quickly Sat and Sun with highs in the 40s and 50s. Backdoor cold front will slide into the area Monday, cooling things down a bit before a clipper system supports much warm weather by Tues as highs will reach the 50s and 60s, with a few 70s possible over SW SD. Active northern stream will persist the rest of next week with chances for precip at times with fluctuating temps.

AVIATION

(For the 00Z TAFS Through 00Z Friday Evening) Issued At 518 PM MDT Thu Apr 2 2026

A storm system will impact the region tonight into tomorrow. Conditions will begin to deteriorate through this evening with MVFR/IFR conditions in low clouds and rain showers (snow showers across northwestern SD) increasing in coverage across the region. Widespread MVFR/IFR conditions expected by around 06z tonight. Rain will transition over to snow for most areas by around 12z tomorrow morning. In addition to the precip and low clouds, winds will shift to the northwest tomorrow morning with gusts of up to 30kt over northeastern WY and portions of southwestern SD.

UNR WATCHES/WARNINGS/ADVISORIES

SD...Winter Storm Warning from midnight tonight to 3 AM MDT Saturday for SDZ001-002-012>014-078. Winter Storm Warning from 3 AM Friday to 3 AM MDT Saturday for SDZ024-025. Winter Weather Advisory from midnight MDT /1 AM CDT/ tonight to 3 AM MDT /4 AM CDT/ Saturday for SDZ026-031-032-043-046-047- 049-072-073. WY...Winter Storm Warning from 3 AM Friday to 3 AM MDT Saturday for WYZ056-057-060. Winter Weather Advisory from 3 AM Friday to midnight MDT Friday night for WYZ054-055-058.